Battery level detection for low power devices

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Battery level detection for low power devices [Copy link]

In zigbee product design, low-power devices often use button batteries or dry batteries. It is necessary to detect the battery voltage to remind the backend or customers to replace the battery. Because our company uses CC2530, I can directly collect the VDD voltage.

But when collecting, please pay attention to the fact that in most batteries, the internal resistance increases as the remaining power decreases. The higher the internal resistance, the lower the battery voltage. In wake-up mode, when the battery outputs the highest current value, the voltage reduction will reach its maximum value. For example, when providing 20mA of current, a new AA battery may not drop below 1.5V, but will drop to 1.0V when it is close to the end of its life.

Therefore, when discharging at a high current, the battery voltage can be used as a visual indication of its remaining power. So in software design, pay attention to reading the power level when the device wakes up or when the battery discharge rate is high.

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This amount of electricity is not very standard, but it is commonly used in practice.

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The battery voltage can be used as a visual indicator of its remaining charge, but this is not accurate, especially for AA batteries.

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The battery charge and voltage are not in a linear relationship, and different batteries have different internal resistances. Sometimes when a battery is no longer in use, the voltage will slowly rise, but at this time the remaining charge obviously does not increase with the increase in voltage.

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Learned to read the power level in wake-up mode or when the battery discharge rate is high.

懒猫爱飞

Use voltage instead of power measurement. 1) It is best to do several sets of charging and discharging curve tests, as well as voltage curves with and without load, and then choose the value to replace 2) There are three situations in the general program: one, no load, two, with load, and three, charging. Only by distinguishing these three situations, using voltage as power indication will be more accurate.